Installed the 1.9's on Saturday. Over the last few days my car seems to be pulling harder especially between 4500-6000 rpm. Why would performance improve over 3 days of driving? Does the pcm adjust itself to this mod? I have an overkill pcm and Will said I would not have to send it back after I did the rockers. Also, would the exhaust change after this because it seems alot deeper now...